Ivanishvili, a multibillionaire philanthropist who became Georgia's prime minister, has repeatedly promised to investigate alleged abuses by officials appointed by President Mikhail Saakashvili, whose party was unseated in the election.

Under a constitutional reform due to take effect after Saakashvili leaves office in October 2013, most of the president's powers will be transferred to the prime minister. But Ivanishvili has moved to establish control without waiting for the formal transfer of authority.

Kardava's lawyer, Kakha Shonia, said that he was specifically accused of involvement in the alleged abduction of one of Ivanishvili's bodyguards in the run-up to the parliamentary vote. The bodyguard disappeared shortly before the election and reappeared in a video statement shortly after, declaring his decision to break ties with his boss and also released tapped phone conversations between opposition leaders, intended to cast them in negative light.

After Ivanishvili's victory, the bodyguard said he had been abducted and acted under pressure.

The new arrests follow the arrest earlier this month of Bacho Akhalaia, a former defense and interior minister, who was accused of abusing servicemen. His supporters have called the case politically motivated.